Tow trucks or wreckers in the past included large cranes or boom arms mounted in truck beds which utilized a hoist mechanism to lift an end of a vehicle for towing. The hoist mechanisms employed various types of slings and chain arrangements attached with bumpers, frames or bodies of the vehicle for lifting and towing. Vehicles manufactured at the time of these early tow trucks generally had bumpers, frame assemblies and vehicle bodies manufactured from heavy gauge steel or sturdy materials which were strong enough to support the vehicle during towing by such sling and chain lifting arrangements.
Cars in more recent years typically have been manufactured with bumpers, frames and bodies formed of lighter weight steels and synthetic materials. Such lighter weight materials have generally been utilized to increase fuel efficiency, lower manufacturing costs and provide shock-collapsible bumpers and flexible air dams. As a consequence of these developments, the rigidity of the vehicle bumpers, air dams and other structures is significantly less than in prior vehicles. Towing with conventional sling and chain arrangements has often damaged the bumpers, frames or bodies of these newer vehicles.
To address these problems, various tow truck and lifting apparatus designs have been attempted to lift and tow a vehicle by the wheels or tires instead of by the frame, body or bumper. For example, towing apparatus have been employed utilizing a straight bar or double-legged bar in conjunction with a towing boom and restraining straps to cradle part of a wheel or tire for towing. These straight bar and double-legged bar devices which are inserted in grooves in the towing boom or a connected cross bar have also caused damage and interference with the rear surfaces of a tow vehicle during turning. During turning, the straight bar or double leg bars or arms are pushed sufficiently forward within the wheel holding devices such that a portion of the arm or bar reaches the bumper face of the tow vehicle. Other wheel lift towing devices have been attempted using a straight bar or two-legged curved bar which is hinged or pivoted to rotate from a towing boom into a towing position to engage a part of a tire in conjunction with the towing boom for towing a vehicle. An example of such rotating bars can be seen in U.S. Pat. No. 4,678,392 to Capers et al.
Many of these towing devices, including devices utilizing straight and double-legged bars, claw, collar and sliding lift mechanisms have required extensive set-up of the towing device and the tow truck at the towing site, often including set-up prior to positioning the tow truck adjacent the vehicle to be towed. Such set-up, in some of these designs, has generally required sliding the straight or curved bar into a groove of a towing boom or connected cross bar prior to positioning of the tow truck. One such wheel lift towing apparatus is depicted in U.S. Pat. No. 4,573,857 to Porter. Other types of towing devices have included claws or collars which slide into an arm attached to a towing boom and are designed to cradle the wheels, as shown, for example, in U.S. Pat. No. 4,968,052 to Alm et al.
The set-up involved in many of these towing devices required the tow truck operator to transport the towing device in a dismantled state, dismount the tow truck, and then assemble and/or extensively set-up the device. Towing devices requiring set-up were typically transported on the tow truck in an unassembled condition, thus increasing the time of utilization and the possibility of losing elements of the towing devices. Such set-up could include, for example, sliding the towing bar it into the towing boom or cross bar or assembling pieces of the towing device at the towing site. Then, the operator had to re-enter the truck, position the truck, and dismount the truck again to secure the towing apparatus. Such extensive set-up and assembly requirements often increased the difficulty of attaching towing devices to vehicle wheels, especially where the vehicle to be towed required quick removal from a highway, bridge, parking garage or space or other dangerous or confined area.
Another type of towing device has been attempted utilizing remote operation such as the device depicted in U.S. Pat. No. 4,473,334 to Brown ("Brown"). Brown describes lifting and towing equipment including a pair of two-pronged, wheel engaging claw members, each of which rotates by remote operation into a towing position. The device is activated by contacting the tire with the prong closest to the towing truck such that the rear prong is rotated into place around the tire. Such a remotely operated towing apparatus can be difficult to maneuver and can require movement and alignment of the entire tow truck to position the wheel lifting apparatus.
There is therefore a need for a wheel lift towing apparatus which easily can be positioned to lift various size tires of a vehicle for lift towing and which minimizes set-up prior to alignment of the towing device and tow truck with the vehicle to be towed. There is also a need for an improved lift towing apparatus which can be transported in an assembled condition to and from a towing site. There is a still further need for a lift towing apparatus which will not damage or interfere with the tow vehicle during turning or towing of a vehicle.